Both the Illinois and Mississippi Rivers have gone from very low levels in winter, to flood stage in spring, and now back to very low levels (first two graphs). Both rivers struggled with the 2012 drought into early 2013. However, above-average rainfall (first map) in April, May, and June, across the upper Midwest caused a rapid raise in the water levels in both rivers that lasted until July. The pendulum swung back the other way since July with much drier conditions prevailing across much of the Midwest (second map). As a result, water levels once again dropped on both river systems and are at or near where they were earlier this year.
With the NWS forecast out to 14 days showing below-average precipitation and the NWS outlook for both October and for October-December showing even odds on above, below, and near-average precipitation, recovery could take some time.
You can look at current and past river and stream levels at this USGS site. While I chose two river gauges to illustrate the changing levels, other sections of the rivers may have responded differently because of control structures and such.